CARBON 13 AND OXYGEN 18 ISOTOPE RECORD OF THE EARLY EOCENE NAMMAL FORMATION, SALT RANGE, PAKISTAN

Abstract

The Nammal Formation is the lowermost unit of the Early Eocene succession in the Salt Range, Pakistan. It is well exposed throughout the Salt Range. The Nammal Formation having 30 to 35 meters thickness is predominantly composed of nodular limestone interbedded with marl and shale. The present study was focussed on stable carbon 13 and oxygen 18 isotopic analysis based on data from two stratigraphically importantsections. The samples from the Nilawahan section provided with the δ13C values varied between 1.34 to -1.56‰ (VPDB) and values of δ18O fluctuated between - 4.47 to -6.59‰ (VPDB). Likewise the sample analysis of BadshahPur section exhibited that the δ13C values changes from1.09 to -1.65‰ (VPDB) and δ18O values rangefrom -4.17 to -6.85‰ (VPDB). The isotopic records of carbon 13 and oxygen 18 indicated the shallow marine deposition of the Nammal Formation under tropical conditions. It highlighted the palaeoclimatic and diagenetic conditions of the Nammal Formation at the time of deposition in the Salt Range region.